Refitting cylinder head

[30csl]

Hi guys,

i finally collected the head from the shop where they skimmed it - they said it was a touch bent but nothing too bad and is still within tolerances.

Any tips on refitting the head? Should i put some hylomar on the gasket or just bare surfaces and the gasket?

Also to remove liquid from the bolt holes do i just use a dowel wrapped with cloth?

Hoping to have her back on the road before the weather really bombs out here.

Thanks,
Rohan

 

[sfdon]

clean the bores with a rag and compressed air.

 

[bill]

I was advised to spray both sides of the gasket with Permatex "Copper Spray-a-Gasket," which I did. Seems to work very well after 1000 miles already. The new gasket probably specifies torquing the bolts in three stages BY DEGREES, instead of by increasing torque in three stages. I made a protractor marked off in degrees that I was able to use with my straight beam torque wrench to set the bolts properly. Good luck, and remember to take your time and have a beer afterwards...

 

[m_thompson]

I was advised to spray both sides of the gasket with Permatex "Copper Spray-a-Gasket," which I did.

That is what I always use.

 

[deQuincey]

i will take advantage of this thread to ask about the torque specification process for the head bolts

i have three sources with different information, the autobooks, the haynes, and the car's manual

as they are different, i would like a definitive version if anyone has one

regards

 

[MMercury]

i will take advantage of this thread to ask about the torque specification process for the head bolts i have three sources with different information, the autobooks, the haynes, and the car's manual as they are different, i would like a definitive version if anyone has one

I am not aware of "a definitive version" but it does appear that on this specific subject, your sources are somewhat out of date, or put another way - unrevised. This may be expected with a 40-year-old car and where there is little monetary incentive for publisher revisions. Perhaps more definitive, for your purposes, is BMW's June 1986, technical service bulletin 11 09 85 (1106). In that bulletin, BMW revised its previous head bolt torquing recommendations. (See below) However, if you keep reading, there may be more to consider.

I am no expert, but there is probably nothing inherently wrong with the factory's 40-year-old torquing prescription as found in the shop manual. Many engines with cylinder heads that were attached using the "old method," somehow manage to remain on the road today. The more modern "angle-torque-method," presumably allows for more accurate and consistent loading/tightening of the bolts and consequently, the head. It is therefore seemingly the preferred torquing procedure. (Whether the logic of the angle torquing is a byproduct of BMW's eventual use of torque-to-yield head bolts is unclear, but the Felpro catalog seems to support this notion.) Head bolts that were used on the M10 and M30 engines were reusable. If they measure to spec, and show no signs of galling or distortion - when compared to a new bolt, I have no problem re-using them.

Although it is hard to quarrel with the information contained in the service bulletin, I would tend to place equal, if not greater, reliance on the instructions found with new head gaskets as being more up-to-date. The gasket manufacturers would likely implement the most current thinking regarding head bolt torquing procedure. After all, one would expect that the gasket manufacturers do not wish to encourage premature failure of their gaskets (although failure might sell more gaskets!) The factory, on the other hand, has less of an incentive to get things perfect, since most 40-year-old cars are . . . out of warranty!

Of incidental interest might be the bulletin's discussion of a 1-year shelf life for pre '82 head gaskets. These gaskets were evidently not plastic shrink wrapped. The bulletin claims that unsealed gaskets are prone to drying out, which seems surprising, considering the anticipated abuse a gasket receives after installation. Does this mean that new gaskets have a presumptive "freshness date" and that gaskets with disturbed shrink wrapping should be discarded after one year? You have to draw your own conclusions! :wink:

Copper spray adhesive as mentioned by others has always seemed like cheap insurance and a good idea to me. Still, note that the service bulletin expressly warns against using any sealant except where the head mates with the upper timing case cover.

Interestingly, if you use ARP studs, instead of the head bolts, ARP suggests the following: "PRELOAD (TORQUE) RECOMMENDATIONS 7. Following the manufacturers recommended torque sequence tighten the nuts in three equal steps to 90 ft lbs." http://arpinstructions.com/instructions/201-4602.pdf http://issuu.com/arpbolts/docs/cata...issuu.com/v/light/layout.xml&showFlipBtn=true

Lastly, head gasket manufacturer, Felpro, has a catalog with current recommendations for use of its gasket on the M30 head. It suggests "5" incremental torquing steps and omits any specific mention of angle torquing!

2985cc SOHC (M30B30) 12 Valve 1978-75 1st 25-32 [lb/ft], 2nd 49-52, 3rd 56-59, 4th warm engine, 5th 56-59 again, 6th retorque after 600 miles 87. (lb/ft) http://olybrake.com/pdf/fel_pro_torque_specs_guide.pdf

"Check Head and Block Finishes
Surface finish is critical for a good seal. FEL-PRO® engineers recommend a micro inch surface finish between 60 to 100 Ra (400 to 800 Rz) for cast iron heads and blocks, 50 to 60 Ra (200 to 600 Rz) for aluminum heads and blocks, and 10 to 30 Ra maximum (500 Rz maximum) for multi-layered steel (MLS) applications. Check the finishes with a profilometer or another type of surface finish comparator. Check for a preferred waviness height of .0004"/.0005" with a waviness peak spacing of .100" (these values are usually associated with milling machines). Always consult your manufacturer’s service manual for surface finish requirements."

"Warm Engine and Retorque Head
Run the engine to normal operating temperature after torquing head bolts. Heat expansion and contraction can radically change the torque readings. Retorque all head bolts to the correct settings while the engine is still warm. If working with aluminum components, let the engine cool completely first. Remember that FEL-PRO® PermaTorque® designs do NOT require retorquing."


"Torque-to-Yield Head Bolts
Torque-to-yield is a method used by most current engine manufacturers to tighten head bolts. The head bolts are torqued to their yield point, which may permanently stretch the bolts. This results in a more even clamping force over the entire area of the gasket. Bolts should first be tightened to a specified torque (measured in foot-pounds), and then tightened an additional partial turn (measured in degrees) to the bolt yield point. The inexpensive FEL-PRO® Torque-to-Angle Indicator (part number TRQ-1) will help you accurately measure the required partial turn in degrees. Because the head bolts may have stretched, the engine manufacturer may recommend against reusing them. Consult the OEM manual on head bolt reuse. Since you may not know how many times a T-T-Y bolt has been removed and reinstalled, FEL-PRO engineers suggest that it is always a good idea to use new bolts. FEL-PRO head bolt sets are available for many domestic and imported engines. The Torque Tables™ indicate which engines have bolt sets offered in the FEL-PRO product line. "

 

[30csl]

Thats a great help - MM thanks for such detailed answers to this thread and my other queries over the years. When/if you are in London i will buy you some beers!

Bill - I will have more than one when its done and tested!

 

[deQuincey]

thanks jay

there is another issue, that several sourcesmentioned the retorue procedure after some hundreds of miles, while others say that is absolutely forbidden to do such a thing, because oil should have made its way through the threads and thus cause a dangerous situqtion that may result in over torquing the bolts and destructionof the threads

any reaction ?

 

[HB Chris]

Retorquing moves the bolt so little that you don't have to worry about oil. My head gasket specified foot/pounds, not degrees.

 

[dp]

1) I clean the bolt holes out with q-tips, basically swabbing crud out of there,
then a shot of solvent, then q-tips again...repeat until the q-tips come out fairly clean

2) I prefer to re-use headbolts, carefully chase the threads clean with a die (used bolts "won't stretch" and chasing threads makes it easier to trust torque readings as accurate and matched bolt-to-bolt

3) I've never used copper gasket treatment or any other gasket treatment before, IF the head has been machined to a close-tolerance T.I.R. flatness (total indicator reading) AND the block isn't warped/pranged, s/b fine.